I hear you. That's also one of my pet peeves too.
Just this past Sunday, I had 4 people go by me on Mt Diablo with music playing through speakers. Not the same as the wilderness, but still very inconsiderate to other hikers IMHO.
I always pack earphones for when I'm watching a video at camp after a hard day's hike. Only time I don't use them is when I'm sure there are no other people anywhere within miles of me.
Never complained, but probably would if I was in the wilderness somewhere and someone came by with music blaring.
